[quote=@gcold]
I doubt the Legion would conscript someone at the age of 13. Either he lied to join, pressured by peer, or taken by more unorthodox commanders. [/quote]

It's not very usual but I've seen some documented cases of child soldiers in WWI at the very least (as an example of child soldiers in legitimate armies, and not some African warlord's drag band). And 'camp people' were a thing, be they traders, washers, cooks or prostitutes.